This creates conflict right away. If she's exaggerating, I want to know why she's having trouble sleeping. If she literally hasn't slept in three days, I want to see the effects of that, since it's very dangerous.

No. I'm on the fence here, though. I am curious why she hasn't slept, but I feel like the fact that she hasn't slept could be shown rather than told. Honestly it's hard to critique this without any more. If the next few sentences are great then this could be fine, but as it stands alone, it doesn't do it for me.

I was debating on this. If the second sentence was strong, it could carry it, but on its own it felt like maybe she was exaggerating rather than literally being sleepless for 3 days. I'm intrigued, but could you show it rather than tell us?

Here's my problem with these kinds of starters: The story isn't about the fact that Emma hasn't slept in three days. The story is about either what has interrupted her sleep or what happens because she hasn't slept. The line needs at least a teaser of that to get me interested.

Yes. But, I'd hope that the next couple of sentences give an interesting or intriguing reason for the lack of sleep. It grabs me because obviously not sleeping that long is not normal, and I want to know why.

No. I think more is needed to set the opening scene. Alot of us go days without sleeping ....I know I have. So what makes this characters story different? Adding a little more hook will turn this around.

No. Too many reasons she might not have slept that are not interesting. Insomnia, new baby, new job - I think you need more specificity in the first line - something that leaves the reader wanting the second line.

It's borderline, but I'm interested enough in "why?" to keep reading. And I like that it's a simple, clean sentence. Makes me think I'll enjoy the writing, that I won't get bogged down in unnecessary dependent clauses or excessive description.